The incident occurred when the minibuses, packed with passengers including women and children, were traveling from Obe district to the city of Herat, the provincial capital.

Herat, which borders Iran and Turkmenistan, had been relatively peaceful, and U.S.-led NATO forces handed over control of security operations in the provincial capital to Afghan forces last month as part of the security transition process.

A statement from Afghan President Hamid Karzai said that two land mines placed by "enemies of the Afghan people" struck the minibuses at 8:30 Thursday morning.

No group immediately claimed responsibility, but Abdul Raouf Ahmadi, a spokesman for the regional police, blamed anti-government Taliban insurgents. Roadside bombs are among the Taliban's deadliest weapons.

“This is the work of the Taliban and other anti-government groups," Ahmadi said, adding that the bombs had been freshly planted.

The victims were on their way to Herat city for shopping for the Eid holiday that marks the end of the Muslim holy month of Ramadan in two weeks.

The U.S.-led military coalition, the International Security Assistance Force, said that children and five women were among the dead.

"Insurgents plan attacks such as these without regard for the civilians they kill, looking for the attention of the media," said Rear Adm. Hal Pittman, an ISAF spokesman.

Taliban insurgents have stepped up attacks on NATO and Afghan forces across the country. Also on Thursday morning, a suicide bomber detonated a vehicle filled with explosives at the gate of a U.S. military base in the eastern province of Paktia and killed two Afghan guards, officials said. The Taliban claimed responsibility for the attack.

More Videos

Mexican man whose killing of woman on San Francisco pier launched national immigration debate found not guilty

Jurors found Jose Ines Garcia Zarate not guilty of murder on Thursday in the killing of Kate Steinle on a San Francisco pier in a case that touched off a national immigration debate. Zarate had been deported five times and was wanted for a sixth deportation when Steinle was fatally shot in the back in 2015. Garcia Zarate didn't deny shooting Steinle and said it was an accident. Before the shooting, the San Francisco sheriff's department had released him from jail despite a federal immigration request to detain him for deportation. Its "sanctuary city" law limits cooperation with U.S. immigration authorities. President Donald Trump cited the case during his campaign in a bid to show the country needed tougher immigration policies.